GlobalWebIndex, a market research firm, found that 42 percent of the hookup app's users were either in a relationship or married, even though half of them identified themselves as single.

Men also make up 60 percent of Tinder's user base, the April 24 report said.

Tinder, however, has rejected GlobalWebIndex's research.

"The results of this tiny, 681-person study in the U.K. is a totally inaccurate depiction of Tinder's user base—this firm is making guesses without having any access to real data on our millions of users worldwide," Tinder said in a statement.

GlobalWebIndex later countered in a statement sent to CNBC, noting that its study's data "is based on interviews with a more than 170,000 Internet users worldwide annually, the largest on-going study into the digital consumer—it's not guesswork, and not just the U.K., as Tinder has suggested."

"We only publish statistically robust numbers, and self-reported survey data is widely recognized as an effective way of understanding consumer behavior," the research firm added.

GlobalWebIndex said that Tinder is still being outpaced by the larger online dating sites like Match.com and OKCupid. Only 1 percent of Internet users worldwide use Tinder on a monthly basis, while 31 percent visited an online dating site in the last month, it said.